A crustose species that is entirely granular sorediate and forms forms moderately thick, yellow-green thalli that are usually broken up into irregular, coarse areoles. Soredia may initially form at the thallus margin. Apothecia, witn yellow-orange discs and a green-yellow margin, tend to be immersed before they become sessile.
Thallus: K+ purple or K- (in deep shade)
In Scotland, Caloplaca citrina agg. is widespread on nutrient-enriched or calcareous substrata such as limestone, concrete, mortar and asbestos cement. BLS distribution map
scottishlichens.co.uk 